Upgrading the Cisco ONS CL to Release 7.0

Transcription

1 This document explains how to upgrade Cisco ONS CL Cisco Transport Controller (CTC) software from Release 5.x or Release 6.x to Release 7.0.x, or from Release 7.0.x to a later maintenance release of 7.0.x. Contents Before You Begin, page 1 NTP-U167 Prepare for Upgrade to Release 7.0, page 3 NTP-U168 Back Up the Software Database, page 4 NTP-U169 Upgrade to Software R7.0, page 5 NTP-U170 Install Public-Key Security Certificate, page 11 NTP-U171 Revert to Previous Software Load and Database, page 12 Related Documentation, page 14 Obtaining Documentation and Submitting a Service Request, page 15 Before You Begin Before beginning, write down the following information about your site; the data will be useful during and after the upgrade: Date, Street Address, Site Phone Number, and Dial Up Number. Read all procedures before you begin the upgrade. This upgrade is supported only for Software Releases 5.x and 6.x upgrading to Release 7.0.x, or for maintenance upgrades from an earlier release of 7.0.x to a later one. Corporate Headquarters: Cisco Systems, Inc., 170 West Tasman Drive, San Jose, CA USA Copyright 2005 Cisco Systems, Inc. All rights reserved.

2 Before You Begin Release 7.0 supports parallel upgrades for multiple nodes in a network. In a parallel upgrade you can still only activate one node at a time; however, you can begin activation of the next node as soon as the controller cards for the current node have rebooted successfully. When managing end-to-end circuits participating in an ML-series RPR ring across multiple nodes involved in a parallel upgrade, all nodes participating in these circuits must have completed the activation before the end-to-end traffic will resume. Document Procedures Procedures in this document are to be performed in consecutive order unless otherwise noted. In general, you are not done with a procedure until you have completed it for each node you are upgrading, and you are not done with the upgrade until you have completed each procedure that applies to your network. If you are new to upgrading the ONS CL, you might want to check off each procedure on your printed copy of this document as you complete it. Each non-trouble procedure (NTP) is a list of steps designed to accomplish a specific procedure. Follow the steps until the procedure is complete. If you need more detailed instructions, refer to the detail-level procedure (DLP) specified in the procedure steps. Throughout this guide, NTPs are referred to as procedures and DLPs are termed tasks. Every reference to a procedure includes its NTP number, and every reference to a task includes its DLP number. The DLP (task) supplies additional task details to support the NTP. The DLP lists numbered steps that lead you through completion of a task. Some steps require that equipment indications be checked for verification. When the proper response is not obtained, a trouble clearing reference is provided. This section lists the document procedures (NTPs). Turn to a procedure for applicable tasks (DLPs). This section lists the document procedures (NTPs). Turn to a procedure for applicable tasks (DLPs). 1. NTP-U167 Prepare for Upgrade to Release 7.0, page 3 This section contains critical information and tasks that you must read and complete before beginning the upgrade process. 2. NTP-U168 Back Up the Software Database, page 4 Complete the database backup to ensure that you have preserved your node and network provisioning in the event that you need to restore them. 3. NTP-U169 Upgrade to Software R7.0, page 5 You must complete this entire procedure before the upgrade is finished. 4. NTP-U170 Install Public-Key Security Certificate, page 11 You must complete this procedure to be able to run ONS CL Software R NTP-U171 Revert to Previous Software Load and Database, page 12 Complete this procedure only if you need to return to the software load you were running before activating the Release 7.0 software. 2

3 DLP- U257 Verify CTC Workstation Requirements NTP-U167 Prepare for Upgrade to Release 7.0 Tools/Equipment Prerequisite Procedures Required/As Needed Onsite/Remote This procedure provides the critical information checks and tasks you must complete before beginning an upgrade. ONS CL nodes to upgrade PC or UNIX workstation Cisco ONS CL Release 7.0 software None Required Onsite or remote Superuser Read the Release s for Cisco ONS CL Release 7.0. Log into the node that you will upgrade. For detailed instructions, refer to the Cisco ONS CL Procedure Guide. Complete the DLP-U257 Verify CTC Workstation Requirements task on page 3. Step 5 If you have multiple ONS CL nodes configured in the same IP subnet, ensure that only one is connected to a router. Otherwise, the remaining nodes might be unreachable. Refer to the Cisco ONS CL Reference Manual for LAN-connection suggestions. When you have completed the tasks for this section, proceed with the NTP-U168 Back Up the Software Database procedure on page 4. Stop. You have completed this procedure. DLP-U257 Verify CTC Workstation Requirements Tools/Equipment Prerequisite Procedures Required/As Needed Onsite/Remote This task verifies all PC or UNIX workstation hardware and software requirements. Before upgrading the workstation to run CTC Software R7.0, complete this task. PC or UNIX workstation None Required Onsite or remote (but in the presence of the workstation) Superuser Ensure that your workstation is either one of the following: IBM-compatible PC with a Pentium III/700 or faster processor, CD-ROM drive, a minimum of 384 MB RAM and 190 MB of available hard drive space, running Windows 98, Windows NT 4.0 (with Service Pack 6a), Windows 2000 Professional (with Service Pack 3), or Windows XP Professional (with Service Pack 1) UNIX workstation with Solaris Versions 8 or 9, on an UltraSPARC or faster processor, with a minimum of 384 MB RAM and a minimum of 190 MB of available hard drive space 3

4 DLP- U257 Verify CTC Workstation Requirements Ensure that your web browser software is one of the following: Netscape Navigator 7.x or higher on Windows Internet Explorer 6.x or higher on Windows Mozilla 1.7 or higher on Solaris Verify that the Java Version installed on your computer is: Java Runtime Environment (JRE) or JRE 5.0, and Java Plug-in or Java Plug-in 5.0 Tip You can check the JRE version in your browser window after entering the node IP address in the URL window under Java Version. The Java Policy file is installed on your computer. For important information on CTC backward compatibility affected by your choice of JRE versions, see the Readme.txt or Readme.html file on the software CD. To install JRE 1.4.2, the Java Policy file, or the Release 7.0 online help, refer to the installation instructions in the Cisco ONS CL Procedure Guide. Return to your originating procedure (NTP). NTP-U168 Back Up the Software Database This procedure preserves all configuration data for your network before performing the upgrade. Tools/Equipment PC or UNIX workstation Prerequisite Procedures NTP-U167 Prepare for Upgrade to Release 7.0, page 3 Required/As Needed Required Onsite/Remote Onsite or remote (but in the presence of the workstation) Maintenance or higher; or Superuser, if performing optional Step 8 Step 5 Step 6 Log into CTC. For detailed instructions, refer to the Cisco ONS CL Procedure Guide. If you are already logged in, continue with. In the node (default) view, click the Maintenance > Database tabs. Click Backup. Save the database on the workstation's hard drive or on network storage. Use an appropriate file name with the file extension.db. (Cisco recommends that you use the IP address of the node and the date, for example db.) Click Save. A message appears indicating that the backup is complete. Click OK. 4

5 DLP- U257 Verify CTC Workstation Requirements Step 7 Step 8 Repeat Steps 1 through 6 for each node in the network. (Optional) Cisco recommends that you manually log critical information by either writing it down or printing screens where applicable. Use the following table to determine the information you should log; complete the table (or your own version) for every node in the network. Table 1 Manually Recorded Data Item IP address of the node. Node name. Timing settings. DCC connections; list all optical ports that have DCCs activated. User IDs; list all, including at least one superuser. Inventory; do a print screen from the inventory window. Network information; do a print screen from the Provisioning tab in the network view. Current configuration (linear, etc.); do print screens as needed. List all protection groups in the system; do a print screen from the protection group window. List alarms; do a print screen from the alarm window. List circuits; do a print screen from the circuit window. Record Data Here (If Applicable) Stop. You have completed this procedure. NTP-U169 Upgrade to Software R7.0 This procedure upgrades your CTC software to Software R7.0. Tools/Equipment PC or UNIX workstation Prerequisite Procedures NTP-U168 Back Up the Software Database, page 4 Required/As Needed Required Onsite/Remote Onsite or remote (but in the presence of the workstation) Superuser Insert the Release 7.0 software CD into the workstation CD-ROM (or otherwise acquire access to the software) to begin the upgrade process. Inserting the software CD activates the CTC Setup Wizard. You can use the setup wizard to install components or click Cancel to continue with the upgrade. 5

6 DLP- U258 Download Release 7.0 Software A traffic interruption of less than 50 ms on each circuit is possible during the activation task, with Ethernet traffic disruption possibly lasting up to several minutes on each circuit. Do not perform maintenance or provisioning activities during the activation task. When managing end-to-end circuits participating in an ML-series RPR ring across multiple nodes involved in a parallel upgrade, all nodes participating in these circuits must have completed the activation before the end-to-end traffic will resume. Complete the DLP-U258 Download Release 7.0 Software task on page 6 for all nodes (or groups of 8 or less nodes) you are upgrading. Complete the DLP-U259 Activate the New Load task on page 8 for all nodes you are upgrading. You can only activate one node at a time; however, you can begin activation of the next node as soon as the controller cards for the current node have rebooted successfully. (Optional) If you wish to ensure that a software revert to the previous software release will no longer be possible, complete the DLP-U258 Download Release 7.0 Software task on page 6 for all nodes, or groups of nodes you are upgrading a second time. Step 5 Step 6 If you download the Release 7.0 software a second time following activation you will never be able to revert to the previous software version. Complete the DLP-U52 Set the Date and Time task on page 11 (any nodes not using SNTP). If you need to return to the software and database you had before activating Software R7.0, proceed with the NTP-U171 Revert to Previous Software Load and Database procedure on page 12. Stop. You have completed this procedure. DLP-U258 Download Release 7.0 Software This task downloads Software R7.0 to the ONS CL nodes prior to activation. Tools/Equipment PC or UNIX workstation Prerequisite Procedures NTP-U168 Back Up the Software Database, page 4 Required/As Needed Required Onsite/Remote Onsite or remote (but in the presence of the workstation) Superuser or Maintenance 6

7 DLP- U258 Download Release 7.0 Software The CTX-CL card has two flash RAMs. An upgrade downloads the software to the backup RAM on the CTX-CL card. The download task does not affect traffic because the active software continues to run at the primary RAM location; therefore, you can download the software at any time. From the View menu, choose Go to Network View. Verify that the alarm filter is not on: a. Click the Alarms tab. b. Click the Filter tool at the lower-right side of the bottom toolbar. Alarm filtering is enabled if the tool is depressed (selected) and disabled if the tool is raised (not selected). On the Alarms tab, check all nodes for existing alarms. Resolve any outstanding alarms before proceeding. During the software download process, the SWFTDWN alarm indicates that the software download is taking place. The alarm is normal and clears when the download is complete. Step 5 Step 6 Step 7 Step 8 Step 9 Return to node view and click the Maintenance > Software tabs. Click Download. The Download Selection dialog box opens. Browse to locate the software files on the ONS CL software CD or on your hard drive, if you are working from a local copy. Open the Cisco15310-CL folder. Choose the file with the.pkg extension and click Open. In the list of compatible nodes, select the check boxes for all nodes you are downloading the software to. Cisco advises that you limit concurrent software downloads on an SDCC to 8 nodes at once, using the central node to complete the download. If you attempt more than eight concurrent software downloads at once, the downloads in excess of eight will be placed in a queue. 0 Click OK. The Download Status column monitors the progress of the download. The software download process can take up to 30 minutes per node, though typically under ten minutes. 1 Return to your originating procedure (NTP). 7

8 DLP- U259 Activate the New Load DLP-U259 Activate the New Load This task activates Software R7.0 in each node in the network. Tools/Equipment PC or UNIX workstation Prerequisite Procedures DLP-U258 Download Release 7.0 Software, page 6 Required/As Needed Required Onsite/Remote Onsite or remote (but in the presence of the workstation) Superuser Cisco recommends you run the optional Cache Loader pre-caching utility in 3 or the activation task. If you do not plan to run the pre-caching utility, Cisco recommends that the first node you activate be a LAN-connected node. This ensures that the new CTC JAR files download to your workstation as quickly as possible. Step 5 Step 6 Step 7 Record the IP address of the node. The IP address is on the upper left corner of the CTC window. Verify that the alarm filter is not on: a. Click the Alarms tab. b. Click the Filter tool at the lower-right side of the bottom toolbar. Alarm filtering is enabled if the tool is depressed (selected) and disabled if the tool is raised (not selected). On the Alarms tab, check all nodes for existing alarms. Resolve any outstanding alarms before proceeding. Click the Maintenance > Software tabs. Verify that the protect version is 7.0 (the release you are upgrading to). Click Activate. The Activate dialog box appears with a warning message. Click Yes to proceed with the activation. The Activation Successful message appears when the software is successfully activated. Click OK in the message box. When you click Yes, CTC will lose connection to the node and will display the network view. Step 8 After activating the node, the software upgrade reboot occurs as follows: Each card in the node resets, beginning with the expansion card. The CTX-CL card will then reset and come back up. When the CTX-CL is finished, the Ethernet card comes back up, followed by reset of the Electrical and optical ports. The whole process can take up to 8 minutes, This process is service affecting, so Cisco recommends that you activate the new load during a maintenance window. Time-division multiplexing (TDM) traffic can endure a hit of up to 50 ms. Expect Ethernet traffic to remain down from the time the expansion card resets, until all cards have finished resetting and come back up (this will take 3 to 8 minutes). After the common control cards finish resetting and all associated alarms clear, you can safely proceed to the next step. (If you are upgrading remotely and cannot see the nodes, wait for 5 minutes for the process to complete, then check to ensure that related alarms have cleared before proceeding.) 8

9 DLP- U259 Activate the New Load Step The upgrade process is service affecting, so Cisco recommends that you activate the new load during a maintenance window. Time-division multiplexing (TDM) traffic can endure a hit of up to 50 ms. Ethernet traffic may remain down from the time the CL-CTX cards switch to the time all Ethernet cards have finished resetting. In CTC, choose File > Exit. In your browser window, click Delete CTC Cache. A confirmation dialog box is displayed. Click Yes to confirm. You must ensure that CTC is closed before clicking the Delete CTC Cache button. CTC behavior will be unreliable if the button is clicked while the software is still running. It might also be necessary to delete cached files from your browser s directory, or from the temp directory on your MS Windows workstation. If you have trouble reconnecting to CTC, complete the DLP-U260 Delete Cached JAR Files task on page Close your browser and then reopen it. (Optional) Run the Cache Loader pre-caching utility, which can improve your speed logging back into CTC after an upgrade. Perform the following steps to run the Cache Loader. a. Load the Release 7.0 CD into your CD-ROM drive. If the directory of the CD does not open automatically, open it. b. Double-click the setup.exe file to run the Installation Wizard. The CTC installation wizard dialog box opens. c. Click Next. The setup options dialog box opens. d. Choose Custom, and click Next. The custom options dialog box opens. e. Select Cisco Transport Controller, and CTC JAR files (deselect any other preselected options), then click Next. A confirmation box opens. f. Click Next again. The CTC Cache Loader pre-caches the JAR files to your workstation, displaying a progress status box. g. When the utility finishes, click OK, and then in the wizard, click Finish. Reconnect to CTC using the IP address from. The new CTC applet for Software R7.0 uploads. During this logon, enter your Superuser username and password. Steps 9 through 14 are only necessary after upgrading the first node in a network because cached files only need to be removed from your workstation once. For the remaining nodes, you will still be disconnected and removed to the network view during the node reboot, but after the reboot is complete, CTC will restore connectivity to the node. 5 Return to your originating procedure (NTP). 9

10 DLP- U260 Delete Cached JAR Files DLP-U260 Delete Cached JAR Files Tools/Equipment Prerequisite Procedures Required/As Needed Onsite/Remote This task manually deletes cached JAR files from your browser and hard drive. When you upgrade or revert to a different CTC software load, you must reload CTC to your browser. Before you can reload CTC, you must ensure that previously cached files are cleared from your browser and hard drive. PC or UNIX workstation None As needed. Onsite or remote (but in the presence of the workstation) Maintenance or higher Delete cache files from your browser directory. In Netscape: a. Choose Edit > Preferences > Advanced > Cache. b. Click Clear Memory Cache. c. Click OK. d. Click Clear Disk Cache. e. Click OK twice. In Microsoft Internet Explorer: a. Choose Tools > Internet Options > General. b. Choose Delete Files. c. Select the Delete all offline content check box. d. Click OK twice. Close your browser. You will not be able to delete cached JAR files from your hard drive until you have closed your browser. If you have other applications open that use JAR files, you must also close them. Delete cached files from your workstation (Windows systems only). a. In your Windows start menu, choose Settings > Control Panel > System > Advanced. b. Click Environment Variables. This will show you a list of user variables and a list of system variables. c. In the list of user variables, look for the TEMP variable. The value associated with this variable is the path to your temporary directory where JAR files are stored. d. Open the TEMP directory located in the path you just looked up. e. Select View > Details. f. Select and delete all files with jar in the Name or Type field. Reopen your browser. You should now be able to connect to CTC. 10

11 DLP- U52 Set the Date and Time Step 5 Return to your originating procedure (NTP). DLP-U52 Set the Date and Time Tools/Equipment Prerequisite Procedures Required/As Needed Onsite/Remote If you are not using SNTP, the upgrade procedure can cause the Date/Time setting to change. Perform this task to reset the date and time at each node. PC or UNIX workstation None As needed Onsite or remote (but in the presence of the workstation) Superuser If you are using SNTP, you do not need this task. In CTC node view, click the Provisioning > General tabs. Set the correct date and time, then click Apply. Repeat Steps 1 and 2 for each remaining node. Return to your originating procedure (NTP). NTP-U170 Install Public-Key Security Certificate Tools/Equipment Prerequisite Procedures Required/As Needed Onsite/Remote This procedure installs the ITU Recommendation X.509 public-key security certificate. The public-key certificate is required to run Software R4.1 or later. None This procedure is performed when logging into CTC. You cannot perform it at any other time. This procedure is required to run ONS CL software. Onsite or remote Provisioning or higher Log into CTC. If the Java Plug-in Security Warning dialog box appears, choose one of the following options: Grant This Session Installs the public-key certificate to your PC only for the current session. After the session is ended, the certificate is deleted. This dialog box will appear the next time you log into the ONS CL. Deny Denies permission to install the certificate. If you choose this option, you cannot log into the ONS CL. 11

12 DLP- U52 Set the Date and Time Grant always Installs the public-key certificate and does not delete it after the session is over. Cisco recommends this option. View Certificate Allows you to view the public-key security certificate. After you complete the security certificate dialog boxes, the web browser displays information about your Java and system environments. If this is the first login, a CTC downloading message appears while CTC files are downloaded to your computer. The first time you connect to an ONS CL, this process can take several minutes. After the download, the CTC Login dialog box appears. If you need to return to the software and database you had before activating Software R7.0, proceed with the NTP-U171 Revert to Previous Software Load and Database procedure on page 12. Stop. You have completed this procedure. NTP-U171 Revert to Previous Software Load and Database This procedure restores the software and database provisioning you had before you activated Software R7.0. Tools/Equipment PC or UNIX workstation Prerequisite Procedures NTP-U167 Prepare for Upgrade to Release 7.0, page 3 NTP-U168 Back Up the Software Database, page 4 NTP-U169 Upgrade to Software R7.0, page 5 Required/As Needed As needed Onsite/Remote Onsite or remote (but in the presence of the workstation) Superuser The tasks to revert to a previous load are not a part of the upgrade. They are provided here as a convenience to those wishing to perform a revert after an upgrade. If you have performed all necessary procedures up to this point, you have finished the software upgrade. Before you upgraded to Software R7.0, you should have backed up the existing database at all nodes in the network (this is part of the NTP-U168 Back Up the Software Database procedure on page 4). Cisco recommends that you record or export all critical information to your hard drive. If you need to revert to the backup database, use the following tasks, in order. Log into the node. For detailed instructions, refer to the Cisco ONS CL Procedure Guide. If you are already logged in, continue with. Complete the DLP-U261 Revert to Protect Load task on page 13. If the software revert to your previous release failed, complete the DLP-U262 Manually Restore the Database task on page 14. Stop. You have completed this procedure. 12

13 DLP- U261 Revert to Protect Load DLP-U261 Revert to Protect Load This task reverts to the software you were running prior to the last activation and to restore your database to the provisioning you had prior to the activation. Tools/Equipment PC or UNIX workstation Prerequisite Procedures NTP-U167 Prepare for Upgrade to Release 7.0, page 3 NTP-U168 Back Up the Software Database, page 4 NTP-U169 Upgrade to Software R7.0, page 5 Required/As Needed Required for revert Onsite/Remote Onsite or remote (but in the presence of the workstation) Superuser To perform a supported (non-service-affecting) revert from Software R7.0, the release you want to revert to must have been working at the time you activated to Software R7.0 on that node. Also, a supported revert automatically restores the node configuration at the time of the previous activation. Thus, any configuration changes made after activation will be lost when you revert the software. The exception to this is when you have downloaded Release 7.0 a second time, to ensure that no actual revert to a previous load can take place. In this latter case, the revert will occur, but will not be traffic affecting and will not change you database. Step 5 From the node view, click the Maintenance > Software tabs. Verify that the protect software displays the release you upgraded from. Click Revert. Revert activates the protect software and restores the database from the previous load. A dialog box asks you to confirm the choice. Click Yes. This begins the revert. CTC drops the connection to the node and takes you to the network view, displaying a confirmation dialog box. Click OK and wait until the software revert finishes before continuing. The system reboot might take up to 4 minutes to complete. Step 6 Step 7 Wait one minute before reverting another node. After reverting all of the nodes in the network, close and restart your Netscape or Internet Explorer browser and log back into the last node that was reverted. This uploads the appropriate CTC applet to your workstation. It might also be necessary to delete cached files from your browser s directory or from the TEMP directory on your MS Windows workstation. If you have trouble reconnecting to CTC, see the DLP-U260 Delete Cached JAR Files task on page 10. Step 8 Return to your originating procedure (NTP). 13

14 DLP- U262 Manually Restore the Database DLP-U262 Manually Restore the Database This task manually restores the database. If you were unable to perform a revert successfully and need to restore the database, perform this task. Tools/Equipment PC or UNIX workstation Prerequisite Procedures DLP-U261 Revert to Protect Load, page 13 Required/As Needed As needed Onsite/Remote Onsite or remote (but in the presence of the workstation) Superuser Do not perform these steps unless the software revert failed. This process is service affecting and should be performed during a maintenance window. Step 5 Step 6 In the CTC node view, click the Maintenance > Database tabs. Click Restore. The Open dialog box appears. Select the previously saved file and choose Open. The database will be restored and the CL-CTX card will reboot. When the CL-CTX card has rebooted, log back into CTC and verify that the database is restored. Wait one minute before restoring the next node. You have now completed the manual database backup. Return to your originating procedure (NTP). Related Documentation Release-Specific Documents Release s for Cisco ONS CL Release 7.0 Release s for Cisco ONS MA Release 7.0 Release s for Cisco ONS SDH Release 7.0 Release s for Cisco ONS Release 7.0 Release s for Cisco ONS Release 7.0 Release s for Cisco ONS Release

15 Obtaining Documentation and Submitting a Service Request Platform-Specific Documents Cisco ONS CL and Cisco ONS MA Procedure Guide, Release 7.0 Cisco ONS CL and Cisco ONS MA Reference Manual, Release 7.0 Cisco ONS CL and Cisco ONS MA Troubleshooting Guide, Release 7.0 Cisco ONS CL and Cisco ONS MA Ethernet Card Software Feature and Configuration Guide, Release 7.0 Cisco ONS SONET TL1 Command Guide, Release 7.0 Cisco ONS SONET TL1 Reference Guide, Release 7.0 Obtaining Documentation and Submitting a Service Request For information on obtaining documentation, submitting a service request, and gathering additional information, see the monthly What s New in Cisco Product Documentation, which also lists all new and revised Cisco technical documentation, at: Subscribe to the What s New in Cisco Product Documentation as a Really Simple Syndication (RSS) feed and set content to be delivered directly to your desktop using a reader application. The RSS feeds are a free service and Cisco currently supports RSS version 2.0. This document is to be used in conjunction with the documents listed in the Related Documentation section. Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R) Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental. Copyright 2005, Cisco Systems, Inc. All rights reserved. 15

16 Obtaining Documentation and Submitting a Service Request 16